This invention relates generally to material handling in a manufacturing environment requiring multiple steps to be performed at distinct locations and more particularly to parts transfer through coating and curing stations of a coating and curing system.
It is known to use conveyor systems to automate the transfer of parts between various work stations. One example of such a part indexing and positioning apparatus is disclosed in two related patents, Acker et al., U.S. Pat. No. 4,942,956 and Acker et al., U.S. Pat. No. 5,012,918, (collectively xe2x80x9cAcker et al.xe2x80x9d) the disclosures of which are illustrative as to the state of the art of push rod conveyors. Acker et al. disclose vertically spaced conveyors of an electrocoating line for intermittent transport of a series of parts through equi-spaced work stations. Acker et al. disclose an over/under conveyor system for an electrocoating line in which parts are coupled to a load bar which is received in a carrier member or a slide bar for transfer through a lower level conveyor of an electrocoating section and an upper level conveyor of a curing section. Push units urge the slide bars and the received load bars coupled to the parts to slide along rail assemblies in a stepped fashion.
Another conveyor system for work pieces is described in Published European Patent Application EP 1 050 495 A2 filed by Eisenmann Corporation, the disclosure of which is instructive regarding the general configuration and operation of walking beam conveyors. The Eisenmann system includes a lower conveyor line, an upper conveyor line, and a pair of lift or transfer mechanisms at the end of each line constructed for moving a work piece. A travel and hoist mechanism and a beam assembly (or walking beam conveyor) are provided for discontinuously moving work pieces along the lower line and raising and lowering them for treatment. The lifting mechanisms include reciprocating arms which are extendable and retractable to facilitate loading and unloading parts onto the upper drying line chain driven conveyor.
The illustrative embodiment is a curing and coating system conveyor for transferring of parts between stations of an electrocoating process with a walking beam conveyor on a lower level, and transferring the same parts through a curing section using a push rod conveyor on an upper level. A loadbar assembly is provided including a segment bar attached to a loadbar to which the parts are coupled. The length of the segment bar influences the incremental distance the push rod conveyor transfers each part during each cycle of a curing process occurring in the curing section.
The illustrative embodiment comprises a two-level coating and curing system with the lower level comprising a plurality of coating or coating related stations spaced along a series path and the upper level comprising a curing section disposed generally congruently above the coating section. A walking beam conveyor advances parts to be coated through the coating section. A push bar conveyor advances the parts through the curing section. The parts are carried on load bar assemblies, each comprising a transversely extending load bar that cooperates with the walking beam conveyor and longitudinally extending segment bars that cooperate with the push bar conveyor. Preferably, the segment bars are rigidly attached at opposite ends of the load bar such that the load bar assembly is an I-shaped or double T-shaped assembly. The length of the segment bars establish the length of each step of the part along the push bar conveyor in the coating section. The distance of the horizontal movement of the walking beam conveyor establishes the length of movement of the part between stations in the coating section. The stations in the coating section are equally spaced apart such that the distance between the centerlines of adjacent stations is equal to the distance of the longitudinal movement of the walking beam conveyor.
The system comprises a lifting conveyor at an exit end of the coating section to raise parts from the coating section to the curing section. The system also comprises a lowering conveyor for accepting parts (load bar assemblies) from the exit end of the curing section. As the push bar conveyor moves load bar assemblies through the curing section step-by-step, the load bar assembly adjacent the exit end of the curing system is pushed by the push bar conveyor onto the lowering conveyor.
The curing section typically will comprise a heating section and a cooldown section. The coating section will typically comprise a plurality of pretreatment stations, a coating station such as an electrocoating station, and a plurality of rinse stations.
The walking beam conveyor comprises an outer frame that moves vertically to raise and lower the parts into stations of the coating section and an inner frame coupled to the outer frame. The inner frame moves longitudinally relative to the outer frame to advance parts to the adjacent station. The inner frame carries saddles for receiving opposite ends of the load bars. The longitudinal displacement between adjacent saddles on the inner frame is equal to the distance between centerlines of adjacent coating stations. Illustratively, the longitudinal range of motion of the inner frame relative to the outer frame is equal to the longitudinal displacement between adjacent saddles and the distance between centerlines of adjacent coating stations.
The loadbar assemblies, one for each part or substrate being moved through the coating system, are provided to cooperate with the walking beam conveyor, the push bar conveyor, the lift conveyor transferring parts upwardly from the coating section to the curing section, the lowering conveyor which removes parts from the curing section, and a conveyor system which feeds the coating and curing system and transfers coated and cured parts to the rest of factory. The loadbar portion of the loadbar assembly serves to support the parts being conveyed or processed. The segment bars rigidly attached to the loadbar serve as spacers for the indexing section of the push bar conveyor. Many advantages to be discussed herein flow from this preferred loadbar assembly structure.
A coating and curing system for coating and curing a plurality of substrates in accordance with the present disclosure includes a coating section, a curing section, a walking beam conveyor, a push bar conveyor and a plurality of loadbar assemblies. The coating section includes a series of processing stations spaced along a path to coat substrates. The curing section is vertically displaced from said coating section. The walking beam conveyor transfers substrates between processing stations of the coating section and is configured for horizontal and vertical movement of the substrates. The push bar conveyor transfers parts through the curing section. Each one of the plurality of load bar assemblies is associated with a different one of the plurality of substrates. Each load bar assembly has a load bar configured to cooperate with the walking beam conveyor to facilitate transfer of the loadbar and its associated substrate through the coating section and a segment bar attached to the loadbar. The length of the segment bar influences incremental movement of the substrate through the push bar conveyor. The walking beam conveyor is configured to horizontally move substrates attached to loadbar assemblies a first incremental distance between adjacent processing stations during each cycle of the system. The push bar conveyor horizontally moves substrates attached to loadbar assemblies a second incremental distance through the curing section during each cycle of the system.
According to another aspect of the disclosure, a circuit like system for processing parts in a plurality of processing steps includes a plurality of loadbar assemblies, a number of processing stations located on a lower level, a number of processing positions located on an upper level, a walking beam conveyor for transferring parts between the number of processing stations, a push rod conveyor for transferring parts through the number of processing positions, a lifting conveyor for transferring parts beteen the walking conveyor and the push rod conveyor and a lowering conveyor for transferring parts from the push rod conveyor to a lower position. The plurality of loadbar assemblies are provided in sufficient amounts for each part to remain coupled to and associated with its own loadbar assembly throughout the plurality of process steps. Each loadbar assembly has a loadbar to which its associated part is coupled and two segment bars each mounted to an opposite end of the loadbar The number of stations for performing process steps are equidistantly spaced along a path at a lower level. Each station has a stand configured to receive and support a loadbar assembly lowered onto the stand. The number of positions for performing process steps are equidistantly spaced along a path on an upper level. The number of positions is greater than the number of stations. The walking beam conveyor has a number of loadbar receivers which exceeds the number of stations. The walking beam conveyor is configured to lower loadbar assemblies supported in the loadbar receivers onto the stands and the lifting conveyor during transition from an up and forward configuration to a down and forward configuration. The walking beam conveyor lifts loadbar assemblies from the stands and a supply stand during transition from a down and reversed position to an up and reversed position. The walking beam conveyor transfers parts forwardly along the path during transition from the up and reversed position to the up and forward position. The push rod conveyor has push rod configured to urge a loadbar assembly coupled to a part positioned adjacent an entry of the path into spaced apart tracks running above the number of positions. The push rod conveyor is configured so that loadbar assemblies supported by the tracks position their associated parts in the number of positions. The lifting conveyor has a rigid horizontally extending arm configured to support a loadbar assembly thereon. The lifting conveyor is configured for reciprocal movement between a lower position wherein a loadbar assembly received in a last loadbar receiver of the walking beam conveyor is vertically above the top of the horizontally extending arm when the walking beam conveyor is in the up and forward position and an upper position wherein the top of the horizontally extending arm is substantially level with the spaced apart tracks. The lowering conveyor has a rigid horizontally extending arm configured to support a loadbar assembly thereon. The lowering conveyor is configured for reciprocal movement between a lower position and an upper position wherein the top of the horizontally extending arm is substantially level with the spaced apart tracks. The walking beam conveyor transfers each part through the number of stations. The walking beam conveyor and lifting conveyor cooperate to transfer each part to the lifting conveyor. The lifting conveyor and the push rod cooperate to transfer the loadbar assembly associated with each part into the tracks of the push rod conveyor. The pushrod conveyor and the lowering conveyor cooperate to transfer each part to the lowering conveyor and the lowering conveyor transfers each part to the lower position.
Additional features, and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of the preferred embodiment exemplifying the best mode of carrying out the invention as presently perceived.